Exam 3 Flashcards
Locus
location of the gene on chromosome
Allele
one of two or more different genes that my occupy a specific locus on a chromosome
homozygous
having two identical alleles for a given gene
heterozygous
having two different alleles for a given gene
dominant
a gene that is always expressed whether it is present in the homo or heterozygous state
recessive
a gene that is expressed only when it is in the homozygous state
Co-dominant/ Egalitarian
both alleles are expressed in the heterozygous state (AB blood)
amorph or silent allele
a gene that produces no product even in the homozygous state
phenotype
the detectable products of genes only discovered through the description of observed traits or the result of direct testing (Ph-physical trait)
genotype
total sum of genes present on the chromosomes with the respect to the one or more characteristics, regardless of whether or not they produce detectable products
Zeta Potential
decrease in the electrical charge of RBC when it is suspended in a high ionic strength colloidal medium (albumin) also decreases the repulsion of the RBCs
What is the “job” of IgG and IgM in terms of bridging the gap between RBCs?
IgM bridges the gap easier because they are larger than IgG
What is the temp reactivity of IgG and IgM?
IgG reacts at 30-37°C and IgM at 4-27°C
What is the effect of LISS in the Ag-Ab reaction?
The addition of LISS will help the rate of association between antigen and antibody. The rate is increased by lowering the ionic strength.
4 enzymes used in the blood bank
ficin papain trypsin bromelin
AHG effects and what does it do?
useful in detecting IgG and complement
What is dosage?
homozygous gives stronger reactions than heterozygous
- also is a word that describes a significant difference in antibody reaction strength depending on the amount of corresponding antigen present on a reb blood cell. The difference in antigen quantity is determind by the zygosity of the gene coding for the antigen
T/F Lewis antibodies commonly cause HDN and HTR.
False - they can not cross the placenta and they will convert in a transfusion.
What is the genotype and phenotypes of Bombay?
Oh - phenotype hh - genotype
Which precursor type substance for ABH antigens?
Type 2
Name the two stages of RBC agglutination in correct order of sequence.
- sensitization 2. clumping (agglutination)
The reverse or backside test detects the presence or absence of..
Ab using the patient’s serum/plasma Ag using RBC
The forward test detects..
antigens in the patient’s RBC using antisera.
Does Lewis cause HDN? Why?
No, because it cannot cross the placenta and because it is not fully developed in a newborn.
What antibodies most often cause HDN?
Rh
What are you called if you have no Rh antigens?
Rh null
T/F Lewis antibodies are enhanced by enzymes.
True
T/F Lewis antigens tend to become stronger during pregnancy.
False - they become weaker.
T/F Lewis antibodies usually occur without known RBC stimulus.
True
T/F The Lewis system includes soluble antigens that are present in saliva and plasma with antigenic determinants occurring naturally on the RBC surface.
False - they are made in the tissue and are not on the RBC surface.
T/F The Rh system was the first to be discovered and by far the most significant for transfusion practice.
False - the ABO was the first to be discovered and is most significant for transfusion.
T/F Rh Abs react more strongly at 4°C than at 37°C.
False - IgG likes 37°.
T/F Rh Abs can cross the placenta.
True.
T/F Rh Abs are not a frequent cause of HDN.
False
Where would we find anti-A1?
A 2 B A 3 A x A 2
Where would you see mixed field agglutination with Anti-A..?
A3
What % of Caucasians are secretors?
80%
Where would you find anti-AB antiserum?
O blood type
Anti-C antiserum will react with an individual with type..?
R1 R2 (DCe/DcE) r ry (dce/dCE) r’ r’’ (dCe/dcE) Rz r (DCE/dce) any ““C””
When would you do a weak D testing?
if the initial spin is negative for a donor.
What would be a good indication of HDN testing?
Serum Bilirubin DAT - (if + do an elution and antibody ID) Cord blood Hemoglobin
What is dolichos biflorus?
An anti-A1 lectin used to confirm the antigens on RBCs.
Who is a good candidate for Rho-gam?
Rh-negative mothers who deliver Rh-positive babies.
List the H substance demonstrated in order of decreasing reactivity.
O>A2>B>A2B>A1>A1B
What is Landsteiner’s Rule?
Ab are present in plasma only when the corresponding Ag is not present on the RBCs.
Why are cord cells washed?
To remove Wharton’s jelly.
Secretor status test used for H substance
inhibition and neutralization tests
Why is Anti-AB antiserum used in the lab?
Detection of subgroups of A weaker than A2
If you have two parents that are A1/A1 and A1/A2, what is the phenotype of their offspring?
A
If you have MM and MN, which agglutinates more strongly? Why?
MM, due to the dosage effect. It affects more strongly in the homozygous state.
Will time have an effect on an antigen/antibody reaction?
Yes
Will overcentrifugation cause a false negative in an antigen/antibody reaction?
No - it is more likely to give a false positive.
Is a reaction at 4°C clinically significant?
No.
If you decrease serum:cell ratio, does it provide more antibody molecules to the antigen sites available for reaction?
No
Are Lewis antibodies clinically significant?
No
Can nonsecretors secrete ABO substances regardless of ABO group?
No
What is the Rh negative genotype?
dd
For Rh antibodies, which is true? -React better at 37°C then 4°C -Cross the placenta -Frequently cause HDN
All are true
Do some A2 individuals produce Anti-A1?
Yes - 8%
If you had the following blood types, which would react with Anti-C? Dce dce DcE/DcE dCe
dCe
Where does anti-AB antisera come from?
Humans with type O blood.
Which is least useful for studying HDN? -Elution & Antibody ID -Serum bilirubin -Direct antiglobulin -Cord blood hemoglobin -Secretor testing
Secretor testing.
What is the purpose of Rh immune globulin?
To prevent sensitization of the Rh negative mother to the baby’s Rh positive blood.
To truly designate Rh negative:
Blood will not react with Anti-D Proceed to Weak D testing
Which would be useful in detecting secretor status for H substance? 1. A1 lectin 2. Boiled saliva 3. Ulex europaeus extract 4. A cells 5. O cells
- No 2. Yes 3. Yes 4. No 5. Yes Why O cells? Increased H antigen sites.
If a mother is D- and Dw- and a father is homozygous for D antigen, what will their offspring’s genotype be?
100% Dd+
What causes HDN to occur?
Maternal cells lack antigen that fetal cells have. That’s what causes sensitization.
Reverse ABO grouping is inadequate in..
newborns
Name the antisera used in detecting Rh.
Anti-D Anti-C Anti-E Anti-c Anti-e
Another name for F antigen is
compound antigen
What is present when F antigen is expressed on RBCs?
c & e inherited on the same haplotype.
Which will react with Anti-F? DCe DcE Dce dCe dcE Dce
Dce
With R1R1 individuals (DCe/DCe), if given dce, what antibody will most likely form?
Anti-c
Which blood group reacts most strongly with Anti-H lectin (Ulex europaeus)?
Group O
The ____________ is the total sum of genes present on the chromosomes with respect to one of more characteristics, regardless of whether or not they produce detectable products.
Genotype
A ______ gene is always expressed whether it is present in the homozygous or heterozygous state.
Dominant
A _______ is a gene that produces no product even in the homozygous state.
Amorph
A ________ gene is expressed only when it is in the homozygous state.
Recessive
The ______ is the detectable products of genes only discovered through a description of observed traits or the result of direct testing.
Phenotype
Name two substances that can reduce the zeta potential and allow red blood cells to approach each other more closely and be agglutinated.
Albumin and LISS
Name two other influencing factors in Ag-Ab reactions.
Ag- temperature, pH, centrifugation, amount of time,
Ab- concentration, ionic strength, dosage
The _____ gene is necessary for the expression of the ABO genes.
H
Ulex europeaus is a lectin with _______ specificity, whereas Dolichos biflorus is a lectin with ______ specificity.
Anti-H and Anti-A
List the three genotypes that produce the A1 phenotype.
A1A1, A1A2, A1O
List the possible genotypes and phenotypes from a mating of AB and BO individuals.
Genotypes: A2B Phenotypes: A1, A2, B1A1, A2B, O
Individuals that do not inherit the H gene have the genotype ____ and are said to have the _____phenotype; they also possess and additional Ab, ________, in comparison to normal O individuals.
hh, Bombay, Anti-H
Lewis antibodies usually occur without known RBC stimulus.
True
Lewis antibodies commonly cause HDN and HTR.
False, Lewis Ab decrease in pregnancy
Give one reason why Lewis antibodies do not cause HDN.
B/C the Lea and Leb Ag are not well developed at birth. Anti Lea and anti-Leb are IgM and cannot cross placenta.
r
dce
r’
dCe
r”
dcE
ry
dCE
R’
DCe
R”
DcE
R0(zero)
Dce
Rz
DCE
Rh genes in order of frequency in Caucasians:
- Most freq: R’-DCe
- 2nd most freq: r-dce
- 3rd most freq: R’‘-DcE
- least freq- ry-dCE
The gene complex which could produce a RBC Ag that reacts with anti-f has both ____ and ____ on the same gene.
c and e
A Rh negative individual has the genotype _____.
dd
State the phenotype of the children of a negative mother who is homozygous for the D ag and a father who is D negative D (weak pos) negative.
All D- Rh +
What test need to be done and what are the results of the test for a donor to be designated as Rh negative.
Weak D Test
Anti-C antiserum will react with the following RBCs.
R’ R’’ r ry r’ r” Rz
the Rh system was the first to be discovered and by far the most significant for transfusion practice
FALSE
The Rh Abs can cross the placenta.
True
Rh Abs are not a freq cause of HDN
False; ABO and Rh are the most common cause
Good indication of HDN(testing wise)?
Bilirubin, DAT(elution and Ab testing), hemoglobin
AHG
Anti-Human Globulin- antisera that contains Ab Coombs test-
Anti-A1
Found naturally occurring in IgM Ab produced by some subgroups of A. Prepared from seeds of plant Dolichos biflorus
Rh Ab characteristics
Well develop[ed at birth so one of the main causes of HDN; Very good immunogens; D most immunogenic after A and B; fewer Ag sites then ABO; not soluble and not expressed on tissues
location of the gene on chromosome
Locus
one of two or more different genes that my occupy a specific locus on a chromosome
Allele
having two identical alleles for a given gene
homozygous
having two different alleles for a given gene
heterozygous
a gene that is always expressed whether it is present in the homo or heterozygous state
dominant
a gene that is expressed only when it is in the homozygous state
recessive
both alleles are expressed in the heterozygous state (AB blood)
Co-dominant/ Egalitarian
a gene that produces no product even in the homozygous state
amorph or silent allele
the detectable products of genes only discovered through the description of observed traits or the result of direct testing (Ph-physical trait)
phenotype
total sum of genes present on the chromosomes with the respect to the one or more characteristics, regardless of whether or not they produce detectable products
genotype
decrease in the electrical charge of RBC when it is suspended in a high ionic strength colloidal medium (albumin) also decreases the repulsion of the RBCs
Zeta Potential
